The present invention relates to a process and equipment for manufacturing and filling bags with multiple cavities and a multiple-cavity bag obtained by said process.
This invention consists of a process and equipment for manufacturing and filling bags, for example the bags intended to contain building materials or other powdery, granular or pasty materials and in particular for containing materials which are meant to be mixed later on in specific proportions, as well as of a multiple-cavity bag obtained by said procedure, each one of said cavities being intended to contain a different type of material and generally intended to be mixed in a pre-determined proportion, said bag being made of a flexible laminar material such as a strip of plastic laminar material.
Until the present time, mortar, a mixture of sand and cement with water, has been made in the building industry on the site itself by means of arbitrarily mixing each of the components in a proportion that is not always right for the purpose which is being pursued.
When large quantities of material are involved, a particular quantity of bags of cement are used with a rough amount of weight in sand or a particular number of bags of sand. In the first of these cases it might occur that an improper proportion may lead to the unsatisfactory strength of the resulting construction and in the second bags of sand and bags of cement are used separately, which on a job site may lead to a disparity between the number of bags of both these products required, with an excessive surplus requiring transport for later use somewhere else, or location in different places of the two types of bag, which means that the operator has to carry out further conveyance.
To solve this problem a bag with multiple cavities has been developed, as well as a process and equipment for making and filling this.
State of the Art
Tubular columns with tubular filling around which a sheet of plastic material is wrapped so that this takes on a tubular shape are well-known. This type of columns prepares and fills a bag with a single cavity, without being able to do this with further cavities.
Patent EES-0554269 refers to a method for continuous preparation of a thermoplastic film bag. In accordance with this invention a tube of thermoplastic film is made and squashed whilst two parallel blades placed opposite each other are formed, then forming two pairs of closed diagonal seams, and finally removing the product obtained.
EP-0397 099 also refers to a method for making bags. This method is of particular use for making bags in a bellows and/or cushion shape, from polyethylene and/or thermo-sealable material, obtained from two sheets of material. This system is not useful either for producing and filling powdery, granular or pasty materials in bags with multiple cavities.
EP-0 593 861 A1 refers to a valve bagging machine. This has a double filling tube which allows sealed filling, preventing materials from escaping from the filling zone. The end pursued in this patent is not that of making and filling multiple cavity bags nor does it allow the problem mentioned to be solved either.
There are conventional bags with a single cavity which can separately contain each of the materials that have to be mixed. In this case the operator has to make the mixture with criteria that are often not very technical, apart from needing to go for two items and having to open each of these.
EP-596497 A1 refers to a bag for liquids intended to be mixed. It has a welding zone, that is relatively weak, so that by means of a slight pressure exerted on one of the two parts of the bag the liquid can be mixed inside this. Nevertheless, given the different nature of the products involved and the ends pursued, its characteristics are substantially different to those of the present invention.
It is well known that in buildings and other kinds of work a mixture of aggregate with cement as agglutinating agent has to be made to join the ceramic or ready-made items concrete for formwork, the last case being less frequent but similarly common due to the simplicity meant by purchasing this from companies supplying ready-mixed concrete.
Another possibility is pre-mixing in the same bag. There may be two different disadvantages, one of a technical nature and another of an economic kind. In the first case the mixing of a normally fairly damp aggregate with a cement would cause a setting or pre-setting which would remove some properties of the mix to be used, this being particularly serious in the event of buildings in which there are normally people present. As a solution to prevent setting there can be a drying process for the particular aggregate in order to remove the residual damp. This would mean an enormous rise in the costs of processing and packaging said products through the use of a power not today applied for said process, apart from needing a drying kiln, also unnecessary today.
One problem found with bags of cement nowadays is that the material of which these are made makes them prone to absorb humidity, which means they cannot be stored outdoors or in particularly damp environments.